The present invention relates to catheters for insertion into a body lumen. More particularly, the present invention relates to a low profile balloon dilatation and/or drug delivery catheter, having a temporary stent for permitting perfusion while positioned within the vascular system.
A wide variety of catheters have been developed in the prior art for percutaneous transluminal coronary or peripheral vascular applications. For example, balloon dilatation catheters for performing percutaneous transluminal coronary angioplasty ("PTCA") are well known in the art.
In general, PTCA is one procedure for treating a narrowed region in an artery, which, in one form, uses a catheter having an expandable balloon thereon. The catheter is percutaneously inserted such as into the femoral artery, and advanced transluminally until the dilatation balloon is positioned within the restricted portion of the lumen. The balloon is thereafter inflated to radially outwardly displace the obstruction to restore some or all of the original interior diameter of the lumen.
Since this treatment modality requires placement of the deflated balloon across- the lesion to be treated, the diameter of the insertion tip of the catheter and deflated profile of the balloon can be limiting factors. This is true either for lesions located in particularly small diameter arteries, or larger diameter arteries having a lesion which occludes a relatively high percentage of the native diameter. Thus, efforts have been in the prior art to produce balloon dilatation catheters having as small a deflated profile as possible.
Other developments in the art include modifying the methodology so that the dilatation balloon remains in an expanded state for a period of time longer than the initial dilatation. Depending upon the medical condition of the patient and clinical judgment, the inflatable balloon may remain in an expanded state for anywhere from several minutes to several hours or longer. Unfortunately, the dilatation balloon necessarily occludes the artery in which it has been expanded, giving rise to a risk of ischemic episodes to the downstream tissue even for relatively short dilatations.
Thus, various efforts have been made in the prior art to produce a balloon dilatation catheter which has some provision for allowing blood flow through or around the balloon during the period of time that the balloon is in the inflated state. Typically, these efforts include the provision of a central through lumen within the balloon, having blood influent ports on one side of the balloon and blood effluent ports on the other side of the balloon. Unfortunately, while these developments may improve the ability to leave the balloon in the dilated state for extended periods, they necessarily enlarge the deflated profile of the balloon catheter. As a result, access to either remote or highly occlusive lesions is limited.
Thus, there remains a need for a catheter which has a minimal deflated or insertion profile for permitting access to remote or highly occlusive lesions, and which at the same time permits sufficient perfusion to minimize the occurrence of ischemic episodes while the balloon is inflated.